Surge drum system



March 30, 1965 s. LIPTON ETAL 3,175,773

SURGE DRUM SYSTEM Original Filed Aug. 10, 1959 2 Sheets-Sheet 1 t 2 l II7 TLJ l9 14 l 6 IO\ l/\\ I2 n's t5 FIGURE-I 464 r-4- I r I I I l l l l3 l I I F IGURE- 3 Sydney Lipton Myron W. Beluga Inventors RolandTimothy Kelley By tent Attorney March 30, 1965 s. LIPTON ETAL SURGE DRUMSYSTEM 2 Sheets-Sheet 2 Original Filed Aug. 10, 1959 FIGURE'Z SydneyLipton Myron W. Beluga \nvenrors Roland Iimofhy Kelley 4 Patent Attorney1 Claim. (Cl. 241-42) This invention relates to a process for preparingan improved rubbery latex, and more particularly it is concerned With anapparatus for providing a surge system. The present application is adivision of parent application SN. 832,827, filed August 10, 1959.

It is known to prepare a butyl rubber polymer in a hydrocarbon solventand to form latex therefrom by dispersing the rubbery solution in anemulsifier solution. In the past, the latex was prepared in a two-stage"homogenization system. The first stage was a dispersator mixer; thesecond stage was a series of rapisonic nozzles and surge capacity wasrequired between the two stages. Furthermore, the average particle sizeof the resulting latex was usually relatively high, above one micron. Itmight have been possible to reduce the size by a conventional recyclingprocedure; however, the internal stability would be relatively poor, andthis is certainly undesirable in a continuous operation.

It has now been discovered that the surge capacity and recycle operationcan be combined and the average particle size of the rubbery latex maybe reduced by incorporating a surge drum system in the process. Thus in'accordance with one embodiment of this invention, a rubbery solution isprepared comprising butyl rubber dis-' solved in a solvent such ashexane. This solution is dispersed in water with an emulsifying agenttherein. The dispersion is passed through 'a high speed mixing zone suchas dispersator. The crude latex eflluent therefrom is then introduced toa surge drum zone wherein a recycle, e.g., 2 to 1 is employed to formcolloidal particles with an average particle size of about 0.5 micronand a particle size range preferably between 0.01 and 1.5 microns. Thislatex is subsequently stored and stripped to provide the final endproduct.

The butyl rubber polymer in this invention is prepared by reacting 70 to99.5 parts by weight, preferably 85 to 99.5, of an isoolefin with 30 to0.5 parts by weight, preferably 15 to 0.5, of multiolefin. Theisoolefin, in general, is a C to C compound, e.g., isobutylene orZ-methyll-butene. The multiolefin, in general, is a C to C conjugateddiolefin, e.g., isoprene, bu-tadiene, or piperylene. The preferredpolymer is obtained by reacting 95 to 99.5% by weight of isobutylenewith 0.5 to by weight of isoprene.

Mixture of monomers, preferably with .1 to 5 volumes of inert diluent,e.g., methyl chloride, should be cooled to a temperature between 0 and-200 C. and it is preferred that the temperature range be between -60and -130 C. The cold mixture is polymerized by the addition of aFriedel-Crafts catalyst, preferably an aluminum halide catalyst in aliquid or dissolved form, in conjunction with vigorous agitation. Theamount of catalyst is generally about 0.15 to 1.0% by weight of themixed olefins.

The polymerization reaction is rapid and the polymer precipitates out ofthe solution in the form of a slurry or fiocculent white solid. Thepolymer, when recovered and dried, has a Staudinger molecular weightbetween 20,000 and 150,000 preferably 45,000 to 60,000; and an iodinenumber between 0.5 and 50, preferably between 1 and 15. The preparationof this copolymer is described in U.S. Patent No. 2,35 6,128. Ahalogenated derivative of nited States Pat butyl rubber, e.g.,chlorinated or bromi-nated butyl rubber is within the purview of thisinvention. The preferred range of halogen in the rubber structure isfrom 0.9 to 1.5 weight percent for chlorinated butyl rubber and 1.5 to3.0 weight percent for brorninated butyl rubber. A polydiolefin rubberand trior tetra-polymers of isobutylene may be applicable to thisinvention.

This invention may be understood from the following description inconjunction with the accompanying drawings in which FIGURE 1 shows theoverall process for preparing an improved rubbery latex. FIGURE 2demonstrates the apparatus for the surge drum zone with the rapisonicnozzles therein. FIGURE 3 provides a detailed illustration of therapisonic nozzle device.

Referring now to FIGURE 1, the butyl rubber cement is introduced intocement stripping zone 2 through line 1. This cement generally comprises14 to 20 weight percent of a rubbery polymer in an over-allhydrocarbonpolymer solution. The solvent is preferably a C to Caliphatic hydrocarbon with 'a boiling point above 175 F The preferredsolvent is hexane. Hex-ane is Withdrawn through line 3 from the top ofstripping zone 2 and a concentrated cement is withdrawn from the bottomportion by means of line 4. This concentrated cement generally comprises21 to 30 weight percent of a rubbery polymer in an over-allhydrocarbon-polymer solution. An emulsifying system is introduced to theprocess through 'line 5 to provide 200 to 500 parts of Water per partsof rubber (phr.). The water which is transported in line 5 containsemulsifiers ranging from 3 to 7 parts phr. Emulsifying agents (surfaceactive agents) found suitable for the improved process of the presentinvention are any of those disclosed in Industrial and EngineeringChemistry for January 1939, pages 6669; January 1941, pages 16- 22;January 1943, pages 1126-130, and any modifications thereof. Preferredemulsifiers are alkali metal, alkaline earth, ammonium or amine salts oforganic sulfates hav ing about 8 to 14 carbon atoms, and preferablyabout 10 to 14 carbon atoms. Emulsifiers having 12 to 14 carbon atomsare especially desirable; and generally they are aliphatic andsaturated, although unsaturated aliphatic and cyclic derivatives may beused. Furthermore, the use of relatively small quantities of a hydrogenortho-phosphate salt increases the mechanical and processing stabilityof these emulsions. It has been found that about 0.25 to about 2 partsof the phosphate phr. are suitable for the production of these highlystabilized emulsion, but it is preferred to use about 0.5 to about 1.5phr. of the stabilizer. The combination of the butyl rubber cement andemulsifying system is transported to dispersator 7 by means of line 6.The purpose of this dispersator 7 is to intimately mix the water,emulsifying agent and rubber to form a crude latex mixture. The averageparticle size of this latex mixture is greater than 1 micron. Themixture from dispersator 7, a crude latex effluent, is subsequentlytransported through line 8 and introduced to surge drum 9. This drumprovides a minimum recycle of 2 to 1 and a latex is formed therein whichhas an average particle size of less than 1 micron. The latex is thenwithdrawn through line 10 and introduced to storage tank 12 Where itremains for about one day to provide stripping surge capacity. The latexis subsequently transported through line 14 to latex stripper 15 whereinthe concentration of the product is increased. The concentrated latextherefrom is withdrawn through line 13. Solvent, e,g., hexane, and Waterare transported through line 16 to an overhead receiver drum 17 toprovide a hexane stream 19 and a water stream 18.

FIGURE 2 is representative of the surge drum zone. Surge drum 9 is acontainer for receiving the dispersion from the dispersator. Secured tothe bottom surface of the surge drum 9 are two vertically disposed weirs26 and 31 in spaced relation that divide the drum transversely intothree sections which are the surge section 22, the first stage section28, and the second stage section 32. The height of weir 31 is largerthan Weir 26. Therefore, each of the three sections of the drum has adiiferent Liquid level therein. At the bottom of the surge section 22 isprovided an inlet means for the crude latex. An outlet means 23 is alsolocated in the bottom portion of the surge section and the latex, whichis withdrawn, is transported by means of pump 24a to a homogenizingmeans, such as rapisonic nozzles 27a and 27!). A rapisonic homogenizerconsists of a gear pump which forces the material through an orifice andimpinges the stream on a knife edge or a vibrating blade enclosed in aresonating bell. One or more nozzle means are disposed in the top of thefirst stage section 28 to introduce the latex from the surge section 22to a point below the liquid level in the first stage section 28. Theflow rates through nozzles 27a and 27b are slightly higher than thecrude latex flow rate in inlet means 20. This provides the first passthrough a set of rapison-ic nozzles. An outlet means 29 is disposed atthe bottom portion of the first stage section 28, and the latex istransported by means of pump 24!) to rapisonic nozzles 34:: and 34b. Oneor more nozzle means are disposed in the top of the second stage section32 to introduce latex at a point below the liquid level therein. Theflow rates through nozzles 34a and 3411 are about the same as thecorresponding flow rates through nozzles 27a and 27b. The outlet flowthrough 33 is less than the flow through line or line 30. As a resultthe excess ilow returns to the first stage section 28 over weir 31 andsubsequently to surge section 22 over weir 26. Flow through line 25 andline must be greater than the crude latex inlet flow and the productoutlet flow. The latex Withdrawn from second stage section 32 by meansof outlet 33 is transported by pump means 240 to a storage tank. Thisdesign provides a minimum of two passes through a set of nozzles. Anabnormal condition is discovered by an electrical alarm means 21 insurge section 22. A minimum amount of instrumentation is required tocontrol the operation in the surge drum zone.

Referring now to FIGURE 3, this drawing shows the detailed apparatus fora rapisonic nozzle 34 in surge drum 9. The latex is transported byconduit means 30 which communicates with nozzle means through valve 48and union 47. The latex from the nozzle passes through union 42. Unions42 and 47 permit removal of nozzle 40 from operation when valve 43 andvalve 48 are closed. Other nozzles such as rapisonic nozzle 34a canremain in operation. Line 30 communicates with 45 which is a flangemounting to support conduit means 46 wherein the latex is introducedbelow the level of the liquid in the second stage section 32.

Thus in accordance with this invention, it is now possible to provide ahomogeneous rubbery latex in which the average particle size is lessthan 1 micron, preferably about 0.5 micron, with a particle size between0.01 and 1.5 microns. This new latex can now be used A rubbery polymerwas prepared comprising 98.8% isobutylene with 1.2% isoprene. A feed wasintroduced to the cement stripper With the rubbery copolymer as "a 19weight percent component of a rubber-hydrocarbon solution with hexane asthe solvent. A concentrated cement was withdrawn from the stripper withthe rubbery polymer as a 23 weight percent component of the solution.

An emulsifying system was prepared comprising 5 parts of Alipal CO-433,330 parts of water, and 100 parts of rubber. This combination of rubberycement and emulsifying system was subsequently passed through adispersator and then introduced to a surge drum at a flow rate of 40g.p.rn. The flow rate through the first set of nozzles was 50 g.p.m. andthe rate through the second set of nozzles was also 50 g.p.m. whichprovides a recycle of 2 to l. The latex was withdrawn from the surgedrum and after one day in storage was transported to a latex stripper;this latex comprised pants of water, 385 parts of hexane and 295 partsof rubber. A concentrated latex was withdrawn from the stripper whichcomprised 100 parts of rubber and 87 parts of water. The averageparticle size of this end product was about 0.5 micron.

Having set forth the general nature and embodiments of the presentinvention, the true scope is particularly pointed out in the appendedclaim.

What is claimed is:

A container for fluid having bottom, top and side Walls, weirs withinsaid container dividing said container into first, second and thirdzones, means providing overflow across said weirs only in the directionfrom said third zone to said second zone and only in the direction fromsaid second zone to said first zone, means for introducing fluid intosaid first zone from outside said container, means for withdrawing fluidfrom the bottom of said first zone, means comprising a rapisonic nozzlefor homogenizing said withdrawn fluid and introducing it into the top ofsaid second zone, means for Withdrawing fluid from the bottom of saidsecond zone, means for homogenizing said fluid withdrawn from saidsecond zone and introducing it into the top of said third zone and means'for withdrawing fluid from the bottom of said third zone.

References Cited by the Examiner UNITED STATES PATENTS 1,399,539 12/21Bonnell z- 209- 2,931,502 4/60 Schoeld 209-170 1. SPENCER OVERHOLSER,Primary Examiner.

ROBERT A. OLEARY, Examiner.

